Ergonomic chair employing stacked layer construction

ABSTRACT

An ergonomic chair employing stacked layer construction including a frame having a seat, a back support, and a plurality of support legs. The seat and the back support each include a plurality of parallel-stacked, thin layered slats, with each of the slats being spaced from one another, and being similarly flexible and securely mounted within a corresponding slot formed in the frame. The parallel-stacked, thin layered slats are subjected to a load with each thin layered slat flexing toward the next lower-positioned slat for progressively increasing the resistance to the load. Each of the slats exhibits linear flexibility and rotational flexibility about a horizontal axis of the slat for adjusting to a shift in the load on the stacked, thin layered slats for providing a comfortable seating surface on the ergonomic chair.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to furniture. More specifically, the present invention relates to methods and apparatus for an ergonomic furniture design that employs a stacked layer construction, and more particularly to an ergonomic chair that utilizes stacked, spaced, thin-layered slats each having similar flexibility for progressively increasing the resistance, the load capacity, and the flexibility of the thin layered slats during a shift in the load.

2. Background Art

The field of ergonomics is directed to an applied science concerned with designing and arranging things, items or articles that people utilize in their work or everyday life so that the people and the things, items or articles interact most efficiently and safely. Thus, ergonomics applies to things present in our daily lives, including furniture. Ergonomic furniture design, particularly ergonomic chair design has become well known in recent years since the intent of such ergonomic furniture design is directed to efficiency and safety. These parameters would include the realm of comfort associated with chairs employed in both the work place and in our private lives. Designing comfort into chairs and other furniture improves the pleasure and productivity associated with the persons utilizing those chairs.

In general, there are two classes of ergonomic chairs. The first class is an office chair having multiple adjustment knobs and levers. This class of ergonomic chair can typically be found in an office supply store. Although, the multiple adjustment knobs and levers of this type of ergonomic chair can be adjusted for the comfort of the user, it is time consuming and tedious to constantly re-adjust the knobs and levers for different individuals. Adjustments must be changed for each person that utilizes the chair to obtain the maximum comfort. Examples of these types of ergonomic chairs can be found on the Internet by utilizing the Google or Yahoo search engines.

A second class of ergonomic chairs comprise chairs that do not have adjustment knobs and levers. Certain chair designs of the past included chairs built that included some flexibility in limited portions of the chair structure. One of those chair designs included a rigid steel frame including steel legs and a hard plastic seating surface firmly bolted to the steel frame. The seating surface includes a surface to support the user's body weight and a non-cushioned back support, all formed as a unitary construction. Some flexibility to body movement existed in this type of hard plastic seating surface. An example of chairs having some level of flexibility built into the chair include lightweight chairs fashioned entirely from plastic. This type of chair has a limited load capacity and is subject to collapse.

Another category of chairs is the non-ergonomic chair including, for example, a solid wood or metal chair found in a classroom or a school or city library. This type of chair essentially exhibits no flexibility. Common problems that exist in this type of chair include a solid, non-flexible construction that will not flex to accommodate the shift in the body weight of a person seated thereon. Thus, these types of chairs tend to be rigid and uncomfortable.

Several references discovered by the Applicant will now be briefly discussed to assist in the understanding of the prior art relating to ergonomic and non-ergonomic furniture. U.S. Pat. No. D239,745 exhibits a Chair comprised of stacked, contacting layers of wood lashed together with a line of cord. U.S. Pat. No. D523,255 discloses a Posture Chair that illustrates a cushioned surface. U.S. Pat. No. 2,125,773 discloses a Seat For Amusement Rides in the form of a toboggan comprising orthogonal slats of wood supported by a frame. U.S. Pat. No. 2,843,195 discloses a Self-Adjusting Back Support having a rigid panel-like backing in front of which there are arranged a plurality of parallel spaced vertically extending strip-like members who ends are arranged to provide an arch or a bow between the anchor points of the strip-like members to support the back of the user's body. U.S. Pat. No. 4,518,202 discloses a Seating Piece Of Furniture including a flexible seating surface that is constructed elastically deformable under load for the purpose of providing comfort.

U.S. Pat. No. 5,292,180 discloses an Upholstered Seating Furniture Having Backrest Provided With Occupant's Upper Body-Conforming Capacity comprising an array of secondary-springs that is attached to and extends convexly forward of a primary-array of springs and covered with resiliently-compressive padding which together rearwardly flex whenever a seated occupant recumbently leans rearwardly to provide an upper body cradling or conforming experience. U.S. Pat. No. 5,383,712 discloses a high density, stacking Flexible Chair having a seat and a curved back support pivotally attached to a frame where the back support can tilt backwards. U.S. Pat. No. 5,544,943 discloses a Seat Construction And Method for upholstered furniture including a rectangular frame with both lateral and horizontal strips of webbing of different elasticity rates attached across the frame to provide support and comfort. U.S. Pat. No. 5,747,140 discloses a Flat Upholstered Body comprising a completed vented upholstered body of stackable contacting grid plates with a wave profile including solid portions of the grid which pass through the extrema of its wave contour. The upholstered body has a high point elasticity despite the plate construction and diffuses stresses without stress peaks so that the work of deformation is absorbed uniformly in the upholstered material resulting in a long service life.

U.S. Pat. No. 6,722,735 discloses a Chair With Synchronously Moving Seat and Seat Back discloses a frame having a seat bottom support and a seat back interconnected by a flexible intermediate portion. U.S. Pat. No. 7,114,782 discloses a Flexible Chair With Stiffener Inserts And Method For Forming A Chair including a hollow frame, a seat and a seat back attached to the hollow frame with stiffeners inserted into the hollow frame. U.S. Patent Publication No. US 2006/0022506 discloses a Pressure Equalizing Mesh having a plurality of connectors resiliently connected to adjacent connectors or displaceable cells and resilient cell connectors for distributing an applied force over an area of the mesh that increases as the applied force increases. Finally, U.S. Patent Publication No. US 2011/0018322 discloses a Chair With Pre-Stressing Structure including a main body and a pre-stressing structure which provides a torsional restoring force for adjusting the back support of the chair.

Notwithstanding, the prior art discovered does not disclose a chair construction that will flex to accommodate the shift in the body weight of a person seated on the chair to maintain a reasonable degree of comfort particularly when seated for a long period of time.

Thus, there is a need in the art for ergonomic furniture, particularly an ergonomic chair employing stacked layer construction wherein a seat and a back support each include a plurality of parallel-stacked, thin-layered slats, where the slats are spaced from one another, have similar flexibility and are securely mounted within slots formed within a chair frame, and where the thin-layered slats are subjected to a load flex toward the next lower-positioned slat for progressively increasing the resistance to the load, exhibit linear flexibility and rotational flexibility about a horizontal axis of the slats for adjusting to a shift in the load on the thin-layered slats for providing a comfortable seating surface over an extended period of time.

DISCLOSURE OF THE INVENTION

Briefly, and in general terms, the present invention provides a new and improved ergonomic chair that employs a stacked layer construction for providing built-in flexibility in a seat and a back support of the ergonomic chair as it relates to the body weight of the person seated in the chair. This built-in flexibility enables the structure of the ergonomic chair to compensate for a shift in the body weight and position of the person seated in the chair to provide greater comfort when seated for long periods of time.

The flexibility and comfort in the seat and back support are provided by utilizing wooden or synthetic slats to fabricate the actual seat and back support surfaces of the ergonomic chair. Consequently, a key feature of the present invention is that the seat and back support of the ergonomic chair incorporates parallel-stacked, thin layered wood or synthetic slats where each slat is separated or spaced from every other slat in the stack. Further, each of the thin layered slats is similarly flexible and is securely mounted within a corresponding slot formed within a chair frame. The wood and synthetic slats are comprised of materials that readily flex without significant resistance. Further, the separation distance between the slats is significantly less than the distance that the slat must be bent or distorted in order to reach the point of structural failure of the wood or synthetic slat. Additionally, the layers of synthetic material could be fashioned from, for example, graphite composite, fiberglass or any other suitable material that exhibits very good “spring back” recovery memory.

The parallel-stacked, thin, layered slats have, by design, a separation distance between the flexible layers which limits the travel of each slat to avoid structural failure. When under load, the top layer will flex into the second layer, the combination of the top layer and the second layer then flexing into a third stacked layer. Each subsequent thin, layered slat flexes less than the previous layer so that the cumulative resistance of the seat and back support surfaces progressively increases. The final thin layered slat in the stack flexes the least. The objective is to provide a design with a degree of flexibility and adaptability with progressively increasing resistance from the first thin, layered slat to the final thin, layered slat in the stack. The overall distance traveled by the flexing slats can be controlled while providing strength to support a significant load.

In practice, the thin, layered slats can be secured in “slots” formed in the chair frame without the use of fasteners or adhesives. Because of their inherent flexibility, the thin layered slats 110 provide both {a} linear flexibility comprising up and down body movements (where the two opposite sides of a slat are at the same distance from the floor), and {b} rotational flexibility with shifting body weight where the two sides of the slat flex about the horizontal centerline of the slat and provide rotation about the horizontal axis (so that the two opposite sides of the slat are not at the same distance from the floor). Thus, the thin layered slats are flexible and will flex to compensate for the shifting body weight of a person seated in the inventive ergonomic chair. The design for the inventive ergonomic chair can be incorporated into dining chairs, school chairs, and the like, e.g., chairs with no moving structures including no height adjustments or chairs that do not have a hinged back support.

Another feature of the present invention includes providing an “empty space” within the thin, layered slats. The “empty space” is located on the seat portion of the ergonomic chair where the user tends to sit when “slouching” on the chair thus practicing bad posture. Sitting on the “empty space” is not comfortable and thus encourages persons to sit-up straight and practice good posture. Further, another feature worthy on note is that the thin layered slats positioned in the back support of the ergonomic chair are oriented or arranged in a staggered manner. The purpose of the staggered arrangement of the thin layered slats in the back support portion of the ergonomic chair is to avoid contact between the user's back with the sharp lower edge of any of the slats to avoid “pressure spots” and ultimate discomfort in the user's back.

The present invention is generally directed to an ergonomic chair employing stacked layer construction including a frame, the frame having a seat, a back support, and a plurality of support legs. The seat and back support each include a plurality of parallel-stacked, thin, layered slats where each of the slats is spaced from one another and each slat is similarly flexible and securely mounted within a corresponding slot formed in the frame. A first layer of the stacked, thin layered slats is subjected to a load. The first layer of slats flexes into a second layer of slats which is spaced from the first layer. Thereafter, the combination of the first layer and the second layer of slats flexes towards a third layer of the stacked, thin layered slats which is spaced from the first and second layers. Each subsequent spaced, thin layered slat is then required to flex less than any of the previous layers of slats which progressively increases the resistance to the load which increases the overall load capacity. More importantly, each spaced, thin layered slat flexes to compensate for a shift in the load on the stacked, thin layered slats for providing a comfortable seating surface.

These and other objects and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate the invention, by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ergonomic chair employing stacked layer construction utilizing spaced, parallel-stacked, flexible thin layered slats in the seat and back support sections of the ergonomic chair for providing a comfortable seating surface.

FIG. 2 is a side elevation view of the ergonomic chair employing stacked layer construction of FIG. 1 showing the parallel-stacked, thin layered slats in the seat section and staggered oriented slats in the back support section.

FIG. 3 is a detail drawing of a plurality of parallel-stacked, thin layered slats located in the back support section of the ergonomic chair of FIG. 1 showing a staggered orientation of the slats and the mounting arrangement of the slats in the frame.

FIG. 4 is a detail drawing of a plurality of parallel-stacked, thin layered slats located in the seat section of the ergonomic chair of FIG. 1 showing the parallel-stacked slats and the mounting arrangement of the slats in the frame.

FIG. 5 is a first schematic diagram of an illustration of progressive flexibility wherein a load is applied to a single thin layered slat to the point of failure.

FIG. 6 is a second schematic diagram of an illustration of progressive flexibility wherein a plurality of non-spaced, parallel-stacked, thin layered slats function as a single thick layered slat exhibiting minimal flex properties.

FIG. 7 is a third schematic diagram of an illustration of progressive flexibility wherein a plurality of spaced, parallel-stacked, thin layered slats each exhibiting a limited flex range with a top first layer slat flexing into a second layer slat, with that combination flexing into a third layer slat for progressively increasing the resistance to a load.

FIG. 8 is an illustration of a laboratory test set-up comprised of a plurality of parallel-stacked, thin layered slats with each slat separated from each adjacent slat by an equal distance and observing the test results upon the application of a fixed load.

FIG. 9 is a schematic diagram illustrating the concept of rotational flexibility wherein the two sides of a thin layered slat flex about the horizontal centerline of the slat when an unequal load is applied to the slat.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an ergonomic chair 100 that employs a stacked layer construction as shown in FIGS. 1-4 for providing built-in flexibility to a seat 102 and a back support 104 of the ergonomic chair 100 as it relates to the body weight of the person (not shown) seated in the chair 100. This built-in flexibility enables the structure of the ergonomic chair 100 to compensate for a shift in the body weight and position of the person seated in the chair 100 for providing greater comfort particularly when seated for long periods of time.

In a preferred embodiment, the present invention is directed to the ergonomic chair 100 that employs the stacked layer construction and includes a chair frame 106 and a plurality of chair support legs 108. Both the chair frame 106 and the chair support legs 108 serve to support the seat 102 and the back support 104 of the ergonomic chair 100 as shown in FIGS. 1 and 2. The flexibility and comfort of the seat 102 and the back support 104 are provided by utilizing wooden or synthetic slats to fabricate the surfaces of the actual seat 102 and back support 104. Consequently, a key feature of the present invention is that the seat 102 and the back support 104 of the ergonomic chair 100 each incorporate a plurality of parallel-stacked, thin layered slats 110. It is noted that each of the parallel-stacked, thin layered slats 110 in the seat 102 and in the back support 104 are separated or spaced from every other corresponding slat 110 in the stack as shown in Applicant's FIGS. 1-4. Further, the separation distance between the slats 110 is significantly less than the distance that the slat 110 must be bent or distorted in order to reach the point of structural failure of the wooden or synthetic slat 110. It is emphasized that each of the thin layered slats 110 in the seat 102 and those located in the back support 104 are identical except that the thin layered slats 110 located in the back support 104 are staggered as shown in FIG. 3. Additionally, the layers of synthetic material could be fashioned from, for example, graphite composite, fiberglass, or any other suitable material that exhibits a very good “spring back” recovery memory to prevent “sagging”. The thin layered slats 110, whether fashioned from wood or a synthetic material will not “sag” because each layer 110 is only permitted to flex within the flexibility range for which the slat material has good spring-back memory.

Reference is now made to FIGS. 5-7 to illustrate the concept of progressive flexibility. FIG. 5 is an illustration of a single thin layered slat 110 attached to and extended between two adjacent parallel stanchions 112. A normal force “F” is applied to the single thin layered slat 110 to the extent that the normal force “F” exceeds the failure-fracture point, represented by the identification number 114, of the slat 110. The normal force “F” represents the weight of a person seated on the single thin layered slat 110. FIG. 6 is an illustration of four parallel-stacked, thin layered slats 110 attached to and extending between the two adjacent stanchions 112. The four thin layered slats 110 are stacked without any separation or spacing between the slats 110. Consequently, the combination of the four contacting slats 110 exhibit the characteristics of a single slat 110 having a four-fold thickness and thus does not exhibit sufficient flexibility to be adaptive to different magnitudes of normal force “F” (e.g., different body weights of potential user's of the ergonomic chair 100). Further, the four thin layered slats 110 never approach the failure-fracture point 114 shown. Thus, the lack of flexibility results in the observation that the illustration of FIG. 6 would not provide a comfortable seating surface.

FIG. 7 is another illustration of four parallel-stacked, thin layered slats 110 attached to and also extending between the two parallel stanchions 112. The four thin layered slats 110 are stacked with a separation or spacing between the slats 110. The separation distance between the four slats 110, the dimensions of and the material comprising the four slats 110 are selected such that the slats 110 will only be permitted to flex to a point that does not exceed the failure-fracture point 114 shown in FIG. 7 when the normal force “F” is applied. Further, each of the thin layered slats 110 is similarly flexible, e.g., the thin layered slats 110 are fashioned from the same wood or synthetic stock having similar dimensions and composition. Thus, the applicable flexibility of each of the slats 110 falls within a specific suitable range. The parallel-stacked, thin layered slats 110 have, by design, a separation distance between the flexible layers which limits the travel of each slat 110 to avoid structural failure. When under load (as when the normal force “F” is applied), the top or first slat 110 will flex into the second slat 110 as shown in FIG. 7. Then the combination of the top or first slat 110 and the second slat 110 flex into the third slat 110. Note that the third slat 110 does not flex sufficiently to cause contact between the third slat 110 and the bottom or fourth slat 110.

Each subsequent thin layered slat 110 flexes less than the previous slat 110 because each slat 110 absorbs a portion of the load so that the cumulative resistance of the seat 102 and back support 104 progressively increases. In the illustration of FIG. 7, the bottom or fourth thin layered slat 110 in the stack flexes the least. The objective of the present invention is to provide a design with a degree of flexibility and adaptability with progressively increasing resistance from the top or first thin layered slat 110 to the bottom or fourth thin layered slat 110 in the stack. The overall distance traveled by the flexing slats 110 can be controlled while providing progressive strength to support a significant load. Thus, FIG. 7 illustrates the concept of progressive flexibility which involves the parallel stacking of multiple layers of thin layered slats 110 where each slat 110 is separated from the next parallel slat 110. When under load (as when the normal force “F” is applied), the top slat 110 will flex downward while yielding to the force “F”. The top slat 110 will then contact the next parallel slat 110 such that the resistance of the two slats 110 is greater than the resistance of just a single slat 110. The feature permits the combination of the first two slats 110 to flex (if the load is sufficiently large) to approach or intersect with a third or subsequent slat 110 such that the resistance increases with the flexibility, all while avoiding the failure-fracture point 114 of any single thin layered slat 110 in the structure.

Another example proffered to illustrate the concept of progressive flexibility is as follows. In a laboratory test set-up conducted by Applicant and illustrated in FIG. 8, the flexibility of a plurality of wooden slats was tested. The plurality of test slats 110 was comprised of mahogany wood having a thickness dimension of one-eighth inch. The one-eighth inch dimension was selected because a slat 110 of this dimension was not too thin and would fit into a one-eighth inch slot that was cut by a one-eighth inch router bit. Further, a one-eighth inch thickness dimension for the slats 110 was not so heavy that it would provide significant resistance to flexibility as illustrated in FIG. 6, e.g., the slat 110 will not flex. Further, each of the test slats 110 was separated from adjacent test slats by a one-eighth inch space. The wood and/or synthetic slats 110 are typically comprised of materials that readily flex without significant resistance.

In the laboratory test set-up illustrated in FIG. 8, five thin layered mahogany slats 110 were stacked on a pair of support blocks 116. The slats 110 were separated by spacers 118 which were approximately one-eighth inch in depth. The five layers of slats 110 were then held in position by threaded clamps 120. A fixed normal force “F” of approximately 160 pounds was applied to the upper surface of the top slats 110 as illustrated in FIG. 8. During the test, it was observed that the top slat 110 flexed downward to contact the second slat 110 which then flexed downward to contact the third slat 110. However, the third slat 110 did not flex downward sufficiently far enough to contact the fourth slat 110. This observation indicated that significantly more weight could be added before the third and fourth slats 110 would be forced to flex downward sufficiently to contact the fourth and fifth slats 110, respectively. This test set-up further illustrates the concept of “progressive flexibility” which {a} enables the parallel-stacked, thin layered slats 110 to progressively increase the resistance to the load from the top or first slat 110 to the bottom or fifth slat 110 in the stack. Further, progressive flexibility {b} promotes the increase in load capacity of the ergonomic chair 100, and {c} enables the flexing of the thin layered slats 110 in the seat 102 and the back support 104 to compensate for a shift in the applied load, e.g., the shifting of the body weight or the person seated in the ergonomic chair 100.

Reference will now be made to FIGS. 1-4 which illustrates the ergonomic chair 100 employing stacked layer construction. An objective of the present invention is to provide the basic simple chair structure with more ergonomics. The basic simple chair structure is as illustrated in FIGS. 1 and 2, e.g., a chair structure that does not have levers and hinges similar to those found in office chairs. Examples of basic chair structures are those found in dining chairs, school and library chairs, and the like, that have no moving structures such as height adjustments and hinged back supports. Office chairs with levers and hinges are not practical at the dining table. Thus, it is the objective of the present invention to provide more comfort to the basic simple chair structure.

FIGS. 1 and 2 illustrate the basic simple chair structure that has been modified to include more ergonomics by employing the inventive stacked layer construction in the form of the parallel-stacked, thin layered slats 110. The use of the thin layered slats 110 provides the chair structure with a greater degree of flexibility in accordance with the objective. The thin layered slats 110 enable the ergonomic chair 100 to adapt to the different body weights and forces to which it is subjected as compared to a similar chair structure having a solid seat surface and a solid back support (i.e., not fitted with the thin layered slats 110). In the inventive ergonomic chair 100 as shown in FIG. 1, there are three separate parallel stacks of thin layers slats 110 shown in the seat 102. The number of slats 110 included in each parallel stack can vary depending on the anticipated distribution of body weight load on the seat 102. Reference to FIG. 2 shows that the two parallel stacks of slats 110 closest to the back support 104 include five thin layered slats 110 while the parallel stack of slates 110 closest to the front of the chair 100 includes just four slats 110. This distribution of the slats 110 is consistent with the distribution of body weight since the majority of the body weight would be in line with the centerline of the human spine resting on the rear portion of the seat 102.

Likewise, there are two stacks of thin layered slats 110 formed in the back support 104 of the inventive ergonomic chair 100. Each of the two stacks includes three thin layered slats 110 for providing support to the user's back. A distinguishing feature between the thin layered slats 110 located within the seat 102 and the thin layered slats 110 located in the back support 104 is that the slats 110 in the seat are parallel-stacked and the slats 110 located in the back support 104 are staggered. It is the intent of the design to give greater travel to the top layer slat 110 where the top layer slat 110 is the slat 110 that makes initial contact with the user's body. When a person sits on the chair 100, the top layer slat 110 is the slat closest to or touching the anterior and the vertical back spine area of the body. It is noted that the slats 110 located in the back support 104 of the ergonomic chair 100 shown in FIG. 2 are oriented such that the top edge of the top layer slat 110 makes initial contact with the person's back.

The purpose of the staggered slats 110 in the back support 104 is as follows. The back support 104 of the ergonomic chair 100 typically leans backwards at an angle relative to a vertical plum line (not shown). If the orientation of the slats 110 in the back support 104 was reversed from that shown, or if no staggering was utilized, then the closest edge of the slat 110 to first contact the user's back would necessarily be the bottom edge of the slat 110. This is the case because (1) the back support 104 is leaning backwards relative to a vertical line, and (2) the natural curvature of the human spine. This arrangement would result in “pressure spots” in the user's back. By selecting the staggering orientation as shown in FIG. 2, the edge of the slat 110 first contacting the user's back is the top edge portion of the slat 110. This design assists in eliminating any “pressure spots” that may develop along the user's back from contacting the sharp lower edge of the slats 110. Thus, the orientation of the staggering of the slats 110 in combination with the natural curvature of the human spine helps avoid the “pressure spots”.

In practice, each of the parallel-spaced, thin layered slats 110 is securely mounted within a corresponding slot 122 formed within the chair frame 106 as is best shown in FIGS. 3 and 4. This secure mounting is achieved without the use of any fasteners or adhesives. FIG. 3 is a detail drawing of a portion of the back support 104 shown in FIG. 1 that illustrates the attachment of the staggered thin layered slats 110 thereto. The slots 122 for the back support 104 are each one-eighth inch slots that are cut into the chair frame 106 by a one-eighth inch router bit. Thus, the slats 110 having a one-eighth inch thickness dimension are sized to cooperatively fit into the one-eighth inch slots 122 of the back support 104. The staggered arrangement of the stack of three thin layered slats 110 are shown anchored in the corresponding slots 122 in FIG. 3. Likewise, FIG. 4 is a detail drawing of a portion of the seat 102 shown in FIG. 1 that illustrates the attachment of the parallel-stacked, thin layered slats 110 thereto. As with the back support 104, the slots 122 for the seat 102 are each one-eighth inch slots that are cut into the chair frame 106 by a one-eighth inch router bit. Thus, the slats 110 having a one-eighth inch thickness dimension are sized to cooperatively fit into the one-eighth inch slots 122 of the seat 102. The arrangement of the parallel-stacked, thin layered slats 110 are shown anchored in the corresponding slots 122 in FIG. 4. The concept of “progressive flexibility” described in conjunction with FIGS. 5-8 limits the load force “F” on the individual slats 110 so that the close fitting tolerance between the edges of the thin layered slats 110 and the slots 122 avoid slippage of the slat 110 from the corresponding slot 122.

Because of their inherent flexibility, the thin layered slats 110 provide both {a} linear flexibility, and {b} rotational flexibility. Linear flexibility is the property of the thin layered slats 110 wherein a linear force such as the force “F” shown in FIG. 7 is applied to the surface area of the slat 110. Typically, the force “F” is a linear force resulting in simple up and down movements such as, for example, up and down body movements employed to rise up from and sit down on the ergonomic chair 100 where no twisting or turning motions are involved. Generally, the two opposite sides of the slat 110 are at the same distance from the floor surface before, during and after the linear force is applied. Rotational flexibility is the property of the thin layered slats 110 during which a non-linear force is applied. The reference to a non-linear force is intended to imply that a force is applied that does involve turning and twisting motions of the user's body while seated in the ergonomic chair 100. This commonly occurs when the user shifts her body weight while seated on the chair.

Reference is made to FIG. 9 which is an effort to demonstrate the response by thin layered slats 110 to non-linear applied forces “F₁” and “F₂”. In FIG. 9, eight thin layered slats 110 are shown. However, the non-linear applied forces “F₁” and “F₂” affects just the two top thin layered slats 110 in the two adjacent left and right stacks as shown with the remaining slats 110 being undisturbed. The force “F₁” is applied to the left stack of the thin layered slats 110 while the force “F₂” is applied to the right stack of the thin layered slats 110. In both situations, the two opposite sides of the slat 110 flex about a horizontal axis 124 of the slat 110 and provide rotation about that horizontal axis 124 as shown in FIG. 9. The result of the application of these forces (“F₁” and “F₂”) is that the effected slat 110 will roll about the edges, that is, rotate about the horizontal axis 124. When this occurs, the two opposite sides of the slat 110 are not at the same distance from the floor as shown in FIG. 9. For example, one edge of the slat 110 in the left stack rotates about the horizontal axis 124 as a result of the force “F₁” so that edge is not at the same distance from the floor as its opposite side. Likewise, one edge of the slat 110 in the right stack rotates about the horizontal axis 124 as a result of the force “F₂” so that edge is not at the same distance from the floor as its opposite side. Thus, the thin layered slats 110 are flexible and will flex to compensate for the shifting body weight of a person seated in the inventive ergonomic chair 100. The design for the inventive ergonomic chair 100 can be incorporated into dining chairs, school and library chairs, and the like, e.g., chairs with no moving structures including no height adjustments or chairs that do not have a hinged back support.

Another feature of the present invention includes providing an “empty space” 126 within the thin layered slats 110 shown in FIGS. 1 and 2. The “empty space” 126 is located on the seat 102 portion of the ergonomic chair 100 where the user tends to sit when “slouching” on the chair 100, thus practicing bad posture. Sitting on the “empty space” 126 is not comfortable and thus encourages persons to sit-up straight and practice good posture. An additional non-illustrated embodiment of the present invention is directed to distributing the thin layered slats 110 orthogonally, that is, perpendicularly in opposing directions, e.g., the slats 110 being aligned in “left-to-right” patterns, or slats 110 being aligned in “up-to-down” or “top-to-bottom” patterns, or slats 110 being arranged in patterns from “front-to-back” of the seat 102. Another embodiment is directed to utilizing the flexible thin layered slats 110 in a design in a “bench” type application where the slats 110 are positioned to provide the comfort feature while avoiding any “sagging” of the thin layered slats 110.

Thus, the ergonomic chair 100 employing stacked layer construction includes a frame 106, the frame 106 having a seat 102, a back support 104, and a plurality of support legs 108. The seat 102 and back support 104 each include a plurality of parallel-stacked, thin, layered slats 110 where each of the slats 110 is spaced from one another and each slat 110 is similarly flexible and securely mounted within a corresponding slot 122 formed in the frame 106. A first layer of the stacked, thin layered slats 110 is subjected to a load. The first layer of slats 110 flexes into a second layer of slats 110 which is spaced from the first layer. Thereafter, the combination of the first layer and the second layer of slats 110 flexes towards a third layer of the stacked, thin layered slats 110 which is spaced from the first and second layers. Each subsequent spaced, thin layered slat 110 is then required to flex less than any of the previous layers of slats 110 which progressively increases the resistance to the load which increases the overall load capacity. More importantly, each spaced, thin layered slat 110 flexes to compensate for a shift in the load on the stacked, thin layered slats 110 for providing a comfortable seating surface.

The present invention provides novel advantages over other ergonomic chair designs known in the prior art. A main advantage of the ergonomic chair 100 employing stacked layer construction is (1) utilizing the concept of “progressive flexibility”, which (2) involves the parallel stacking of multiple layers of thin layered slats 110, (3) where each slat 110 is separated from the next parallel slat 110, (4) and when under load (as when the normal force “F” is applied), the top slat 110 will flex downward while yielding to the force “F”, (5) the top slat 110 will then contact the next parallel slat 110 such that the resistance of the two slats 110 is greater than the resistance of just a single slat 110, (6) enabling the combination of the first two slats 110 to flex (if the load is sufficiently large) to approach or intersect with a third or subsequent slat 110, (7) such that the resistance of the slats 110 increases with the flexibility, (8) all while avoiding the failure-fracture point 114 of any single thin layered slat 110 in the structure.

While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. For example, it is within the scope of the present invention to incorporate the inventive parallel-stacked, thin layer slats 110 into other types of furniture including wooden outdoor patio chairs or school chairs. Both of these embodiments are foreseeable and are within the scope of the present invention.

It is therefore intended by the appended claims to cover any and all such modifications, applications and embodiments within the scope of the present invention. Accordingly, 

What is claimed is:
 1. An ergonomic chair employing stacked layer construction comprising: a frame, said frame including a seat, a back support, and a plurality of support legs; said seat and said back support each including a plurality of parallel-stacked, thin layered slats, each of said slats being spaced from one another, and being similarly flexible and securely mounted within a corresponding slot formed in said frame; and a first layer of said stacked, thin layered slats being subjected to a load, said first layer of slats flexing into a second layer of slats spaced from said first layer, with the combination of said first and second layers flexing towards a third layer of said stacked, thin layered slats spaced from said first and second layers, wherein each subsequent spaced, thin layered slat flexes less than said previous layers of slats, progressively increasing the resistance to said load for increasing the load capacity and for flexing to compensate for a shift in said load on said stacked, thin layered slats for providing a comfortable seating surface.
 2. The ergonomic chair of claim 1 wherein said stacked, thin layered slats are each comprised of wood.
 3. The ergonomic chair of claim 1 wherein said stacked, thin layered slats are each comprised of graphite composite.
 4. The ergonomic chair of claim 1 wherein said stacked, thin layered slats are each comprised of fiberglass.
 5. The ergonomic chair of claim 1 wherein said parallel-stacked, thin layered slats located in said back support are staggered.
 6. An ergonomic chair employing stacked layer construction comprising: a frame including a seat, a back support, and a plurality of support legs; said seat and said back support each including a plurality of parallel-stacked, thin layered slats, each of said slats being spaced from one another, and being similarly flexible and securely mounted within a corresponding slot formed in said frame; and said parallel-stacked, thin layered slats being subjected to a load with each thin layered slat flexing toward the next lower-positioned slat for progressively increasing the resistance to said load, each of said slats exhibiting linear flexibility and rotational flexibility about a horizontal axis of said slat for compensating for a shift in said load on said stacked, thin layered slats for providing a comfortable seating surface. 